public override LambdaExpression VisitValPathOperatorExp(ScimFilterParser.ValPathOperatorExpContext context)
{
var argument = Expression.Parameter(typeof(TResource));
var attrPathExpression = Visit(context.attrPath());
var operatorToken = context.COMPAREOPERATOR().GetText().ToLower();
var valueToken = context.VALUE().GetText().Trim('"');
var isEnumerable = attrPathExpression.ReturnType.IsNonStringEnumerable();
var left = Expression.TryCatch(
Expression.Block(Expression.Invoke(attrPathExpression, argument)),
Expression.Catch(
typeof(NullReferenceException),
Expression.Constant(attrPathExpression.ReturnType.GetDefaultValue(), attrPathExpression.ReturnType)
));
if (isEnumerable &&
attrPathExpression.ReturnType.IsGenericType &&
typeof(MultiValuedAttribute).IsAssignableFrom(attrPathExpression.ReturnType.GetGenericArguments()[0]))
{
// we're filtering an enumerable of multivaluedattribute without a sub-attribute
// therefore, we default to evaluating the .Value member
var multiValuedAttributeType = attrPathExpression.ReturnType.GetGenericArguments()[0];
var multiValuedAttribute = Expression.Parameter(multiValuedAttributeType);
var valueAttribute = multiValuedAttributeType.GetProperty("Value", BindingFlags.Public | BindingFlags.Instance);
var valueExpression = Expression.TryCatch(
Expression.Block(Expression.Property(multiValuedAttribute, valueAttribute)),
Expression.Catch(
typeof(NullReferenceException),
Expression.Constant(valueAttribute.PropertyType.GetDefaultValue(), valueAttribute.PropertyType))
);
var valueLambda = Expression.Lambda(
CreateBinaryExpression(valueExpression, operatorToken, valueToken),
multiValuedAttribute);
var anyMethod = MethodCache["any"].MakeGenericMethod(multiValuedAttributeType);
var anyPredicate = Expression.TryCatch(
Expression.Block(
Expression.Call(
anyMethod,
new List <Expression>
{
left,
valueLambda
})),
Expression.Catch(typeof(ArgumentNullException), Expression.Constant(false)));
return(Expression.Lambda(anyPredicate, argument));
}
return(Expression.Lambda <Func <TResource, bool> >(
CreateBinaryExpression(left, operatorToken, valueToken),
argument));
}
